1) There is Reference field for each album you can use in external program to map it to shelf position
2) or you can utilize two custom fields, for example Shelf No. and Position No.
in each case you will need the external app to read the info from CATraxx DB to highlight the correct spot on the shelf
3) AFAIK, CATraxx stores the No. of selected album (the one you select with your mouse) in the DB, so you can make external app to pick that info as a command to highlight the corresponding spot on the shelf. Multi-selecting should also work.